I'm in the same situation as you and have investigated the idea of working in HK but it seems that you have to be registered with the labour department as a safety officer/auditor first before any contractors will even start to look at your resume.

To be registered, you have to have the right qualifications and so many years of H&S experience gained specifically in HK. I explained my situation to the workplace H&S branch of the labour department i.e. experience, DipNEBOSH, GradIOSH etc. to see if I could register with them, but their response appear to suggest that I do not have the acceptable qualifications and experience to do so.

Back to the old 'chicken and egg' situation...